Is the universe inside a black hole
Pro Research Analysisby 
Searched over 200M research papers
Is the Universe Inside a Black Hole?
Black Hole Structure and Universe Formation
Regular Black Holes and Black Universes
Recent research has explored the concept of "black universes," a type of regular black hole with a unique internal structure. Unlike traditional black holes, which contain singularities, black universes feature an expanding Kantowski-Sachs universe and a de Sitter infinity inside the event horizon. This structure suggests that a hypothetical explorer could survive inside such a black hole, as it lacks the destructive singularity typically associated with black holes. This model proposes that our universe might have originated from a phantom-dominated collapse in another universe, crossing the horizon and undergoing isotropization.
The Universe as a Black Hole
The idea that the universe itself could be a black hole has been a topic of speculation among cosmologists. This theory posits that the universe might be a closed, yet unbounded system, confined to a localized region of space that cannot expand indefinitely. This model could potentially resolve several issues regarding the nature and origin of the universe, aligning with various observations across different wavelengths.
Anisotropic Universes in Black Holes
Another intriguing concept is the formation of a nonsingular, anisotropic universe within a black hole. Using the Kantowski-Sachs metric, researchers have shown that torsion can prevent singularities, replacing them with a nonsingular bounce. This bounce could lead to a finite period of inflation, during which the universe expands and becomes isotropic, resembling our current universe. This model suggests that the interior of a black hole could host a universe that evolves through a series of bounces and expansions.
Transition Between Black Holes and New Universes
S-Branes and Universe Formation
The presence of S-branes inside black holes can induce a continuous transition between the black hole's interior and the beginning of a new universe. This mechanism provides a resolution to both black hole and Big Bang singularities, suggesting that black holes could serve as gateways to new universes. This model also addresses the black hole information loss problem, offering a natural resolution.
Universes Inside Λ Black Holes
Research on Λ black holes, which feature a variable cosmological term, indicates that these black holes can contain an infinite sequence of black and white holes, vacuum regular cores, and asymptotically flat universes. The regular core of a Λ white hole models the initial stages of universe evolution, starting from a nonsingular big bang followed by anisotropic expansion. This model also explores the quantum birth of baby universes inside Λ black holes due to the quantum instability of the de Sitter vacuum.
Quantum Birth and Evolution of Universes
Quantum Birth of Universes
The quantum birth of universes inside regular black holes with de Sitter interiors is another area of interest. This model suggests that a flat universe could emerge from an initial quantum fluctuation, with a small admixture of radiation and strings providing the necessary conditions for quantum tunneling. This process replaces the singularity with a de Sitter space, allowing for the birth of a new universe.
Baby Universes and Black Hole Interiors
A toy model has been proposed to describe an expanding universe inside a black hole. This model involves matching a collapsing matter cloud to an expanding Friedmann-Robertson-Walker universe through a phase transition in the quantum-gravity dominated region. This approach aims to reconcile classical black hole descriptions with the theoretical resolution of space-time singularities, leading to a bounce for the collapsing matter.
Conclusion
The concept of the universe being inside a black hole is supported by various theoretical models and research findings. These models suggest that black holes could host expanding universes, prevent singularities through mechanisms like torsion and S-branes, and even give birth to new universes through quantum fluctuations. While these ideas remain speculative, they offer intriguing possibilities for understanding the nature and origin of our universe.
Sources and full results
Most relevant research papers on this topic